EB-10X Installation & Service Manual |
Motor Data Package
34
Kollmorgen | kdn.kollmorgen.com | October 2020
where T
R
Rated = time/TCTP
Substitute 3) into 4) and obtain:
T
C
T
OUT
T
R
Actual
2
= T
R
Ultimate (1 - e
-t
/TCTP)
To find the time to ultimate temperature, set T
R
actual = T
R
ultimate and solve for t. This
yields the following equation:
(EQ-5)
T
MAX
= -TCTP 1n 1-
2
T
OUT
T
C
where: t = max on time
TCTP = thermal time constant of motor
Tc = continuous torque of the motor at the particular operating speed
T
OUT
= operating torque
This gives the maximum ON time for a given operating torque beginning at ambient
temperature. Examination of this equation reveals that as T
OUT
approaches Tc, t approaches
infinity. This is expected since we can theoretically operate the motor indefinitely at
continuous torque without exceeding its thermal limits. EQ-5, with EQ-2, define the motor’s
operating time limits.
Example #1
An EB-106-B has the torque vs. speed performance characteristics described in the
performance curve labeled EB-106-A PC-26927. The motor is operating intermittently at
4000 rpm with a torque of 2.9 lb-ft.
FIND:
a) maximum ON time without exceeding ultimate temperature
b) the required OFF time for an ON time of 4 seconds
GIVEN: T
OUT
= 2.9 lb-ft
From performance curve (EB-106-A PC-26927), the continuous torque at 4000 rpm is
obtained.
T
C
= 1.5 lb. ft.
From Specifications CD-27133 for the EB-106-B motor:
TCTP = 4 min.
(a) The maximum ON time is found from (EQ-5):
T
MAX
= -TCTP 1n 1-
2
T
OUT
T
C
TCTP = 4 minutes
T
C
= 1.5 lb-ft
T
OUT
= 2.9 lb-ft